Function extractEntities

extractEntities(
composed: Map<string, ComposedNode>,
strings: StringTable,
): EntityExtractionResult
Extract entities from composed IFCX nodes.

Mapping:
- path -> expressId (synthetic, auto-incrementing)
- bsi::ifc::class.code -> typeEnum
- children hierarchy -> spatial structure
Parameters
- composed: Map<string, ComposedNode>
- strings: StringTable
Returns EntityExtractionResult